premultiplied alpha?
No, alpha clipping refers to the amount of clipping applied to the alpha channel in the viewport (that is, what gets transparent and what gets solid in a face with an RGBA texture).

"Premultiplied alpha" refers to one of the two possible alpha modes:


Associated or Premultiplied
Unassociated or "straight" in Blender.


These alpha "modes" define which alpha over formula has to be used for blending the plate over a background.

When alpha is "associated", the alpha-over operation will simply add the foreground plate to the background previously scaled by the foreground's inverted alpha. 

When alpha is "unassociated" (straight), the foreground has to be pre multiplied by its alpha channel before the aforementioned operation, because the pixels with alpha 0 have RGB information that otherwise would be added to the background (and in the case of an unassociated alpha, it's not desired).

The term "pre multiplied" refers in the first case to the fact that the foreground doesn't have to be multiplied by alpha by the over operation, so it's considered as if it was already "pre multiplied". 

For that reason, it's adivisable to avoid the term "pre multiplied" becuase it suggests that there was a multiplication (which actually didn't happen). Alpha is "associated" as if it was already "pre multiplied".

Associated alpha allows more nuanced compositing effects than unassociated, as it allows to composite pixels that are both transparent and luminous, therefore is usually the recommended format for VFX (and it's the format that renderers like Blender's internal and cycles produce).